Physico-Chemical Characterization of an Urban Rainwater (Zagreb, Croatia)

Abstract

The characterization of organic matter (OM) and trace elements (TEs) was conducted in bulk precipitation samples collected in an urban area of Croatia (Zagreb center), from January 2009 to October 2011 (N = 31). Characterization of OM was performed by measurement of dissolved (DOC) and particulate forms of organic carbon (POC), as well as surface-active substances, copper complexing capacity and reduced sulfur species which were determined electrochemically. Concentrations of TEs (Al, Fe, Zn, Cr, Ba, Mn, Cu, Sr, Ti, Pb, V, Ni, Rb, Sb, As, Sn, Se, Co, Cd, Mo) were analyzed by HR ICP-MS. The most important outcome of this study is confirmed relatively low concentrations of DOC (0.69–4.86 mgC L−1) and TEs. Daily fluxes of Zn, Pb, Ni, As, and Cd were two to three times lower than that of those reported for an urban industrial site in Europe. Additionally, this study shows that the value and reactivity of rainwater DOC has not considerably changed if compared with the results from the 1998–1999 study (0.78–4.39 mgC L−1). High traffic density and thermal power plants are assumed to be the main local sources of pollutants in Zagreb. Using Al as a reference element, it was found that Cd, Sb, and Cu were associated with anthropogenic sources. The solubility of Sr, Zn, Cd, Ni, Cr, As, and Rb was higher than 70%. Another critical characteristic of precipitation composition is episodic variation in POC concentration because of Saharan dust transport. Obtained data can be valuable for environmental quality assessment, as well as for insight into atmospheric deposition processes.

Long-Term Trends in 20-Day Cumulative Precipitation for Residential Rainwater Harvesting in Poland

“…The study analysed the presence of trends in the rainfall time-series for 19 cities in Poland for years 1970-2019, from the perspective of design and operation of RWH systems. Therefore, there were analysed the 20-day cumulative rainfall periods along the year higher than the thresholds 10, 20, 30 and 40 mm, as well as the class intervals [0-10) mm, [10][11][12][13][14][15][16][17][18][19][20] mm, [20][21][22][23][24][25][26][27][28][29][30] mm and [30][31][32][33][34][35][36][37][38][39][40] mm. The results of the M-K test detected statistically significant (CLI ≥ 95%) or close to statistical significance (90% ≤ CLI < 95%) trends in 14 of the 152 datasets under analysis (9.2% of the total), and tendencies to change (75% ≤ CLI < 90%) in approximately 18% of the datasets, with less than half of them corresponding to downward trends.…”

“…1% 14% 26% 7% 5% 21% 34% 6% 6% 20% 31% 5% 7% 15% 30% 5% Gdańsk 2% 21% 48% 9% 12% 25% 42% 6% 8% 19% 30% 5% 2% 12% 25% 5% Gorzów Wlkp. 5% 16% 32% 7% 9% 23% 39% 8% 11% 20% 32% 5% 6% 15% 23% 4% Katowice 2% 10% 27% 6% 5% 16% 30% 5% 10% 18% 28% 5% 6% 16% 27% 5% Kielce 0% 14% 33% 7% 5% 19% 31% 6% 11% 21% 33% 5% 6% 16% 30% 5% Koszalin 1% 11% 29% 6% 7% 16% 34% 5% 9% 17% 28% 5% 6% 15% 23% 4% Kraków 2% 12% 28% 6% 6% 19% 35% 6% 9% 20% 33% 6% 6% 16% 25% 5% Lublin 4% 16% 34% 7% 11% 22% 35% 6% 10% 20% 34% 5% 6% 15% 24% 4% Łódź 3% 15% 31% 7% 6% 21% 31% 6% 9% 22% 31% 5% 5% 16% 28% 5% Olsztyn 1% 12% 27% 6% 6% 20% 39% 7% 9% 19% 28% 5% 5% 15% 26% 4% Opole 3% 15% 31% 7% 8% 21% 40% 7% 8% 20% 32% 6% 7% 14% 27% 5% Poznań 6% 18% 36% 9% 13% 25% 37% 6% 11% 22% 34% 5% 2% 14% 25% 6% Rzeszów 1% 13% 33% 7% 9% 21% 44% 7% 9% 20% 36% 6% 6% 14% 25% 5% Suwałki 2% 13% 25% 6% 5% 21% 39% 6% 6% 19% 30% 6% 8% 16% 26% 4% Szczecin 2% 16% 41% 8% 8% 21% 34% 6% 9% 21% 36% 6% 7% 15% 25% 4% The annual fraction with 20-day cumulative rainfalls according to the class intervals of [0-10) mm, [10][11][12][13][14][15][16][17][18][19][20] mm, [20][21][22][23][24][25][26][27][28][29][30] mm, and [30][31][32][33][34][35][36][37][38][39][40] mm was calculated and summarised in Table 3. The annual average frequency of periods with a 20-day cumulative rain between [0-10) mm ranged from 10% for Katowice to 21% for Gdańsk.…”

“…In the case of the interval between [10][11][12][13][14][15][16][17][18][19][20] mm, the smallest average found was 16% (Katowice and Koszalin), while a highest equal to 25% found in three cities: Gdańsk, Poznań and Toruń. For the interval between [20][21][22][23][24][25][26][27][28][29][30] mm, the average fraction of the year ranged from 17% (Koszalin) to 22% (Łódź and Poznań). Zielona Góra registers the highest average fraction of the year with 20-day cumulative rainfall ranging [30][31][32][33][34][35][36][37][38][39][40] mm (17%), and the smallest occurs in Gdańsk (12%).…”

“…To increase the readability of the table, statistically significant changes ( ≥ 95%), changes close to statistical significance ( from 90 to 95%) and tendencies to change ( from 75 to 90%) are highlighted blue (increasing) and yellow (decreasing). There is evidence of statistically significant upward trends for Gorzów Wielkopolski ( [30][31][32][33][34][35][36][37][38][39][40] It is worth noting that for Poznań the amount of 20-day rainfall sums in the ranges [0-10) mm (CLI = 68%) and [10][11][12][13][14][15][16][17][18][19][20] mm (CLI = 91%) decreased, while there was no increase in the ranges [20][21][22][23][24][25][26][27][28][29][30] mm and [30][31][32][33][34][35][36][37][38][39][40] mm. However, let us observe (Table 4) that Poznań is the only city in which a clear upward tre...…”

“…The quality of the collected rainwater depends on the cleanness of the conveying system, atmospheric contamination, the storage conditions and the filtering and treatment processes applied in the RWH system. The stages of passing through the atmosphere and flowing down the catchment determine the rainwater composition, which is affected both by local and long-distance transported dust and aerosols of natural and anthropogenic origin [24][25][26][27][28]. The regional distribution of precipitation also influences the pollution of run-offs.…”